Search the Community
Showing results for tags 'hell creek fm'.
Found 4 results
So I am interested in this neat little dinosaur foot that is supposedly from Leptorhynchos. The initial Leptorhynchos ID was supplied by the seller, but after doing some research I found another hell creek oviraptorid named Anzu. Is there any way to distinguish between the two? Any help would be appreciated.
I noticed a number of online suppliers offering Troodon teeth that actually belong to the genus Pectinodon. Thought it would be a good discussion item for a focused post since they can get confusing with the various morphologies of Pectinodon teeth. I'll use publications to illustrate my points and reflect all Campanian & Maastrichtian age teeth of North America. (Edit) A new paper published late in 2017 has turned this taxon upside down. I will try to reflect those changes here but it should not change alter how they are identified against Pectinodon teeth. Specimens from Dinosaur Park Formation previously assigned to Troodon formosus have been reassigned to a new taxon Latenivenatrix mcmasterae and others to a resurrected Stenonychosaurus inequalis. Troodon formosus is now considered invalid. At the very end of this page I will show my understanding of ID's by Formation. Canadian Journal of Earth Sciences, 2017, Vol. 54, No. 9 : pp. 919-935 Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America Aaron J. van der Reest, Philip J. Currie https://doi.org/10.1139/cjes-2017-0031 Troodontids - Standard morphology These teeth are recurved, laterally compressed and oval in cross section. The Denticles are large and pointed upward on the distal (posterior) carina and minute or absent on the mesial (anterior) carina. Premaxillary teeth have strong denticles on both edges (Figure 8.3 E) Denticles per mm is typically around 4 Maximum length about 9.8mm Figure Examples : Troodontids: Large Morphology The tooth is large about 50% greater and others and can reach 14mm long, recurved and round in cross section. (See figure below 8.3 # 20-21) These have been collected from the North Slope of Alaska. Their is nothing unique to these teeth to describe a new taxon. I've have seen one of these jumbo teeth come from Alberta. Troodon Alaska.pdf Troodontids: Flat Morphology. Sankey paper "Diversity of latest cretaceous small theropods" describes a flat morphology tooth from the masstrichtian deposits, different that Zapsalis teeth that have fine serrations (See figure below 8.3 #1-8) Teeth are straight, with round cross sections. One side is flattened to concave and the other side is convex. Well developed longitudinal ridges are present. The mesial edge is smooth but can have minute denticles. The distal carina are large, larger than any other theropod. Looks like a Zapsalis tooth to me? Pectinodon bakkeri : Comparison - Troodon and Pectinodon Pectinodon - left image #5 mesial denticles usually absent #11 posterior denticles very large and often rounded much smaller average length of 2.6mm Troodonitid right image #12 posterior denticles point to the tip #13 anterior denticles exist, can be large or absent much larger average length 4 mm but can reach 9.8 Scale bar 1mm Pectinodon teeth can be put into four categories: premaxillary, maxillary, anterior & posterior dentary and all look different. In Figure 9.5 A & B are Premaxillary, C & D Maxillary, E & F Anterior Dentary and G & H Posterior Dentary Premaxillary teeth: long and slender, mesial carina strongly convex and distal is straight. Distal Denticles are large, pointed to the tip and become smaller toward the base. Maxillary teeth are compressed and bladelike. They look like small Dromaeosaur teeth. Anterior denticles are irregular in size and very small (5-6 denticles/mm). Posterior denticles are 3 per/mm. Anterior teeth are leaf shaped with no serrations on the mesial carina. Denticles on the distal edge are 1.6/mm. Denticles are irregular in size. Please note scale bar at 5mm References used: 1) Vertebrate Microfossil Assemblages by Sankey and Baszio 2) Dinosaur Systematics by Ken Carpenter and P. Currie North American Troodontids: My best call I"m sure these will be updated with new research and discoveries. Belly River Group (Alberta) : Latenivenatrix mcmasterae and Stenonychosaurus inequalis (one cannot distinguish between isolated teeth of these two species ID: should be Troodontid indet.) Kaiparowits Formation (Utah) : Talos sampsoni Judith River Formation (Montana) : Stenonychosaurus sp. Two Medicine Formation (Montana) : TMF Troodontid Hell Creek & Lance Formation (Montana, Wyoming, South & North Dakota) : Stenonychosaurus sp. All others (Alberta, Saskatchewan, Alaska, Colorado etc) : Stenonychosaurus sp. Multiple Troodontids might exist in these other fauna similar to the Belly Group. Since skeletal remains are super rare we may never know if this is true. Identification to a family level "Troodontid indet." may be more appropriate but you can decide that.
It's September and a great time to go out in the badlands of Montana and South Dakota hunting for Dinosaurs. I try to go out at least twice a year unfortunately family health issues prevented me from a earlier trip so I was happy to be able to go on this one. My South Dakota site is in the upper Hell Creek Formation and full of the hadrosaur Edmontosaurus annectens plus the occasional theropod tooth. All of the bones collected come from this site however some of the teeth I show come from a channel deposit in Montana. I've been collecting this site for 20 years and its still delivering. We are on the edge of a bluff and the fossil layer can be between 2 to 4 feet. Lots of good bones are to be found but we also have lots of punky or junk bones and about 70 % is collectible. The site is quite large and like I said last year we have no idea of its size but it contains scores of hadrosaurs all disarticulated. No skulls are found but all the elements that make up a skull are collected. Some pictures of the site and locality The collecting area is between the white lines My tools are pretty simple and those shown are used 90% of the time. I also use a pick. We have no equipment to remove the overburden so its our biggest challenge and can be quite daunting for those not physically in shape, like most of us The collecting layer starts off with a crumbly pebble deposit where the teeth are found then turns into sand where little is found and most of the bones are in the lower hard clay deposit. Most of the bones fracture when exposed to air so glue may be necessary to keep them together during extraction. I use two Paleobond products : PB4417 which is a field consolidant and comes off easily during prep but does not have structural strength. PB002 is used when I need strength on larger bones. I also carry a debonder just in case I glue my fingers together or as in this trip a fellow collector glued his glove to his hand. Glue can be dangerous since it cures quickly. Its more a safety issue but sometimes needed on bones/teeth in the field. I found this product "Golden West Super Solvent" used in the prep lab of the Royal Tyrrell Museum. Its effective has acetone but had no odor or effects on the skin and is not flammable or volatile. Its more costly than acetone but for the amount I use it works and no smell. In addition to showing everyone what I found I would also like to share the process of extracting some of the bones. Very few get to collect in this formation so it might be interesting to see the process and how hard it is to get from the Dirt to the Finished product.
Although not the same fan fare as with Dinosaurs my collecting days has yielded some very cool turtle specimens. Channel deposits deliver a host of species which include Fish, Crock, Reptiles and Turtle. You never know what the next flip of the knife will deliver and skulls are as good as you can get. Lots of broken ones but every once and a while a complete one surfaces. I am not that knowledgeable on identifying turtle specimens so bare with me if you see something misidentified, just let me know. I have a pet Dog but I call these skulls my PET FOSSILS. They are a lot easier to maintain no walking or feeding required. I don't have names for them but just enjoy them and are always a big hit with everyone. My first skull is in the Trionychid family softshell turtle. Very cool skull looks like it has arms for walking. Identified it as Axestemys byssina (8 1/2" - 22cm) Long Hell Creek Formation Perkins Co., South Dakota The next skull is in the Baenid Family Identified as Bubaena cephalica the atlas vertebra was found with the skull. (3 1/2" -8.9cm) Square Hell Creek Formation Powder River Co., Montana Same as above just slightly smaller specimen at 3" (7.6cm) long, same locality The next skull is also in the Baenid Family Identified as Palatobaena choen approximately 2 1/4" (5.7cm) square. Very odd shaped nasal opening Hell Creek Formation Powder River Co., Montana Same as above just slightly smaller specimen at 2" (2cm) square